code: def StringByteSize(field_number, string):
      return BytesByteSize(field_number, string.encode("utf-8"))
  
imports: import struct
  from google.protobuf import descriptor
  from google.protobuf import message
label_desc: Use image node_id 20 for calling a global function with example usage: StringByteSize(field_number, string) and returns: BytesByteSize